fix(ui): show only first name and increase font size to 22 in CoupleSelectorBandeau

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/widgets/quotidien/couple_selector_bandeau.dart

@@ -149,7 +149,9 @@ class _CoupleCard extends StatelessWidget {
           Expanded(
             child: _MembreTile(
               photoUrl: couple.enfant.photoUrl,
-              name: couple.enfant.displayName(fallback: 'Enfant'),
+              name: (couple.enfant.prenom != null && couple.enfant.prenom!.isNotEmpty)
+                  ? couple.enfant.prenom!
+                  : couple.enfant.displayName(fallback: 'Enfant'),
               fallbackIcon: Icons.child_care,
             ),
           ),
@@ -162,11 +164,13 @@ class _CoupleCard extends StatelessWidget {
           Expanded(
             child: _MembreTile(
               photoUrl: couple.am.photoUrl,
-              name: couple.am.displayName(
-                fallback: mode == CoupleBandeauMode.parent
-                    ? 'Nounou'
-                    : 'Parent',
-              ),
+              name: (couple.am.prenom != null && couple.am.prenom!.isNotEmpty)
+                  ? couple.am.prenom!
+                  : couple.am.displayName(
+                      fallback: mode == CoupleBandeauMode.parent
+                          ? 'Nounou'
+                          : 'Parent',
+                    ),
               fallbackIcon: mode == CoupleBandeauMode.parent
                   ? Icons.volunteer_activism
                   : Icons.person_outline,
@@ -210,7 +214,7 @@ class _MembreTile extends StatelessWidget {
             maxLines: 1,
             overflow: TextOverflow.ellipsis,
             style: GoogleFonts.merienda(
-              fontSize: 18,
+              fontSize: 22,
               fontWeight: FontWeight.bold,
               color: QuotidienTheme.ink,
             ),